(Not Applicable)
(Not Applicable)
The present invention generally relates to a propulsion system for an electric boat, and more particularly to a swivel drive assembly.
Electric boats typically use a direct drive system for propulsion. In such a system, a propeller of the boat is attached to a propeller shaft which extends from the bottom thereof. The propeller shaft extends through the bottom of the boat via a stuffing box which prevents water from entering the boat. Disposed on an end of the propeller shaft opposite the propeller is a pulley. The pulley is coupled to an electric motor via a belt. Accordingly, as the electric motor rotates, the propeller shaft rotates thereby spinning the propeller and pushing the electric boat. By controlling the direction of rotation and speed of the electric motor, it is possible to control the speed and direction of the boat.
In order to maneuver the electric boat, there is typically provided at least one rudder, preferably two. Typically, the rudder is disposed aft of the propeller. By turning the rudder, water flowing thereover will be redirected thereby turning the boat. However, in order for the rudder of the electric boat to be effective, it is necessary for the electric boat to maintain a minimum speed. In this respect, water must flow over the rudder of the electric boat at a prescribed rate in order for the electric boat to turn. At slow speeds, the electric boat will become difficult to handle thereby resulting in an increase of danger to the passengers of the boat because water is not flowing over the rudder at the prescribed rate.
Additionally, as previously mentioned, the prior art direct drive system for the electric boat comprises an elongate propeller shaft extending through the bottom of the boat to the electric motor. The electric motor is mounted to the boat through the use of brackets such that the pulley of the propeller shaft, as well as the drive belt of the electric motor are disposed within a housing in the interior of the electric boat. The housing typically consumes valuable interior space of the electric boat that could be used for passengers.
The present invention addresses the above-mentioned deficiencies in the prior art direct drive systems for electric boats by providing a swivel drive system. The swivel drive system of the present invention consumes less interior space than the conventional direct drive system thereby providing extra interior room for passengers. Additionally, the swivel drive system, constructed in accordance with the preferred embodiment of the present invention, provides an assembly which greatly enhances the maneuverability of the electric boat at slow speeds. In this respect, the swivel drive system is capable of positioning the propeller of the electric boat in a direction which facilitates turning.
A swivel drive assembly for an electrically powered boat. The swivel drive assembly comprising a housing which has a propeller shaft extending therethrough and a propeller mechanically coupled to the propeller shaft. The swivel drive assembly further includes a turning post having a hollow interior mechanically coupled to the housing. A drive shaft is mechanically coupled to the propeller shaft and is disposed within the hollow interior of the turning post and the housing. The swivel drive assembly further includes an electric motor mechanically coupled to the drive shaft and operable to spin the propeller thereby. In this respect, the rotation of the turning post is operative to point the housing and the propeller in a desired direction to facilitate steering of the boat.
In the preferred embodiment of the present invention, the housing further comprises a gear mechanism mechanically coupled to the propeller shaft and the drive shaft. In this respect, the gear mechanism comprises a first bevel gear mechanically coupled to the propeller shaft and a second bevel gear mechanically coupled to the drive shaft and cooperatively engaged to the first bevel gear. Typically, the first and second bevel gears are spiral cut bevel gears in order to reduce noise and vibration of the swivel drive assembly.
In order to prevent water from entering the electric boat, the swivel drive assembly of the present invention further includes a seal mounted to the boat. The seal has an interior bore sized slightly larger than the turning post such that the turning post is extensible through the seal. The seal may include a vibration dampening member configured to reduce vibrations between the swivel drive assembly and the boat. Typically, the dampening member is formed from an elastomeric material.
In the preferred embodiment of the present invention, the seal has a housing with a hollow interior and the dampening member is disposed therein. The dampening member is formed with a cylindrical bore extending therethrough. The seal further includes a cylindrical bushing disposed within the cylindrical bore of the dampening member. The bushing has a hollow interior sized slightly larger than the turning post such that the turning post is extensible therethrough. Additionally, the seal may further include an oil seal disposed adjacent to the bushing and the turning post in order to prevent water from entering the boat from the space between the turning post and the bushing. The seal may further include a bearing disposed adjacent to the bushing and the turning post in order to facilitate rotation of the turning post.
The swivel drive assembly of the present invention may further include a motor mount attached to the electric motor and the turning post. In this respect, as the motor mount is rotated, the turning post is rotated thereby pointing the propeller in the desired direction to steer the boat. Additionally, the electric motor may include an output shaft mechanically coupled to the drive shaft through the use of a spline coupling.
In accordance with the present invention there is provided a method of controlling vibrations in an electrically powered boat having an electric motor, a drive shaft, a propeller shaft, a propeller, and a vibration dampening member. The method comprises attaching the vibration dampening member to the electric boat. Next, the electric motor is coupled to the vibration dampening member and the drive shaft is attached to the electric motor. The drive shaft is extended through the vibration dampening member and mechanically coupled to the propeller shaft. Next, the propeller is attached to the propeller shaft and spun by the electric motor such that vibrations may be created. In the preferred embodiment, the dampening member will reduce the vibrations caused by the spinning of the electric motor and the propeller. In the preferred embodiment, a gear mechanism mechanically couples the drive shaft to the propeller shaft. In this respect, the gear mechanism comprises a first spiral cut bevel gear and a second spiral cut bevel gear which are capable of reducing vibration and noise within the swivel drive assembly of the present invention.